１　疾病的发生和发展存在着内因和外因和任何事物一样，疾病的发生和发展受着外因（包括环境因素）和内因（机体功能状态）的影响，人类疾病常见的外因包括感染、中毒、外伤、理化因素和环境变化等，其作用是显而易见的。从１９～２０世纪，医学的发展对疾病外因的认识和处理? 1 The occurrence and development of disease There are extrinsic and exogenous factors as well as anything else. The occurrence and development of the disease are affected by external factors (including environmental factors) and internal factors (functional status of the organism). Common external causes of human diseases include infection, poisoning, trauma , Physical and chemical factors and environmental changes, its role is obvious. From the 19th to the 20th century, the development of medical knowledge on the external causes of disease and treatment?